Photographic products, processes and compositions utilizing cesium hydroxide



United States Patent "ice 3 276,872 PHOTOGRAPHIC PRbDUCTS, PROCESSES ANDCOMPOSITIONS UTILIZING CESIUM 'HY- DROXIDE George H. Fernald, Jr.,Lincoln, Mass, assignor to Polaroid Corporation, Cambridge, Mass., acorporation of Delaware No Drawing. Filed Dec. 28, 1962, Ser. No.247,867 23 Claims. (Cl. 96-29) This invention relates to photography andmore particularly to products, compositions and processes useful in thedevelopment of photosensitive silver halide elements.

One object of the present invention is to provide novel processes andcompositions for the development of silver halide emulsions, saiddeveloping compositions containing cesium hydroxide.

Another object of (the present invention is to provide novel processesand compositions for the development of silver halide emulsions, inwhich the novel developing composition is capable of developing anexposed silver halide emulsion and imparting a reversed or positiveimage of the developed image to a superposed image-receiving material,wherein the rate of diffusion transfer of colorproviding substances fromsaid emulsion to said imagereceiving material to form the color image issubstantially increased.

A further object is to provide novel processes and compositions suitablefor use in preparing monochromatic and multichromatic photographicimages.

Still another object is to provide novel photographic productscontaining cesium hydroxide as a component of the processingcompositions.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the process involving the severalsteps and the relation and order of one or more of such steps withrespect to each of the others, and the products possessing the features,properties and the relation of elements which are exemplified in thefollowing detailed disclosure, and the scope of the application of whichwill be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description.

The photographic processes and compositions disclosed herein areparticularly useful in the treatment of a latent image present in aphotosensitive element, such as an exposed silver halide emulsion,whereby a positive dye image thereof may be imparted to another element,herein referred to as an image-carrying or image-receiving element.

US. Patent No. 2,983,606, issued May 9, 1961 to Howard G. Rogers,discloses diffusion transfer processes wherein a photographic negativematerial, such as a photographic element comprising an exposed silverhalide emulsion, is developed in the presence of a dye developer toimpart to an image-receiving layer a reversed or positive dye image ofthe developed image by permeating into said emulsion a suitable liquidprocessing composition and bringing said emulsion into superposedrelationship with an appropriate image-receiving layer. The inventiveconcepts herein set forth provide novel liquid processing compositionsfor use in such processes.

In carrying out the process of this invention, a photosensitive elementcontaining a silver halide emulsion is 3,276,872 Patented Oct. 4, 1966exposed and wetted with the novel liquid processing composition of thisinvention, for example by immersing, coating, spraying, flowing, etc.,in the dark, and the photosensitive element superposed, prior to, duringor after wetting, on an image-receiving element. In a preferredembodiment, the photosensitive element contains a layer. of dyedeveloper, and the liquid processing composition is applied to thephotosensitive element in a thin, substantially uniform layer as thephotosensitive element is brought into superposed position with animage-receiving element. The liquid processing composition permeates theemulsion to provide a solution of dye developer substantially uniformlydistributed therein. As the exposed silver halide emulsion is developed,the oxidation product of the dye developer is immobilized orprecipitated in the developed areas, thereby providing an imagewisedistribution of unoxidized dye developer dissolved in the liquidprocessing composition. This immobilization is apparently due, at leastin part, to a change in the solubility characteristics of the dyedeveloper upon oxidation, and especially as regards its solubility inalkaline solutions. It may also be due, in part, to .a tanning effect onthe emulsion by the oxidized developing agent. At least part of thisimagewise distribution of unoxidized dye developer is transferred byimbibition, to a superposed image-receiving layer, said trans-fersubstantially excluding silver or oxidized dye developer. Theimage-receiving layer receives a depthwise diffusion, from the emulsion,of unoxidized dye developer, without appreciably disturbing theimagewise distribution thereof, to provide a reversed or positive,colored image of the developed or negative image. The image-receivingelement may contain agents adapted to mordant or otherwise fix thedilfused, unoxidized dye developer. Imbibition periods of approximatelyone minute have been found to give good results with monochrometransfers and from about one to three minutes with multicolor transfers,but this contact period may be adjusted where necessary to compensatefor variations in temperat-ure or other conditions. The desired positiveimage is revealed by stripping the image-receiving layer from thephotosensitive element at the end of the imbibition period.

The dye developers may be utilized in the photosensitive element, forexample in, on or behind the silver halide emulsion, or they may beutilized in the image-receiving element or in the liquid processingcomposition. In the preferred embodiment, a coating or layer of the dyedeveloper is placed behind the silver halide emulsion, i.e., on the sideof the emulsion adapted to be located most distant from the photographedsubject when the emulsion is exposed and preferably also adapted to bemost distant from the image-receiving layer when in superposedrelationship therewith. Placing the dye developer behind the emulsionlayer, as in the preferred embodiment, has the advantage of providingincreased contrast in the positive image, and also minimizes anylight-filtering action by the colored dye developer. In this preferredembodiment, the layer of dye developer may be applied by using a coatingsolution containing about 0.5 to 8%, by weight, of the dye developer.Similar concentrations may be used if the dye developer is utilized as acomponent of the liquid processing composition. In an especially usefulmode of disposing the dye developers in the photosensitive elements, thedye developer is dissolved in a waterimmiscible solvent and thendispersed in a gelatin coating solution. 7

It has now been found that when a photosensitive element is processedwith a liquid processing composition Containing cesium hydroxide as atleast a portion of its alkaline component, a number of unexpected andhighly beneficial effects accrue as a result of processing with saidcesium hydroxide. Concentrations of cesium hydroxide which have beenfound to be useful in accordance with this invention fall within therange of about 0.1 to about 25%, by weight, the higher concentrationsbeing used when cesium hydroxide is the sole or principal source ofalkalinity.

When photosensitive elements are processed with the novel liquidprocessing composition of this invention, a marked increase indevelopment rate is noted. This substantial rate increase is apparentwhen cesium hydroxide is used as the sole alkaline component of theprocessing composition, as well as when mixtures of sodium hydroxide andcesium hydroxide constitute the alkaline components. f

In addition to an increase in the development rate,the novel cesiumhydroxide-containing processing compositions of this invention alsoprovide a significantly shorter development induction period than, forexample, a so-.

dium hydroxide processing composition, inprocessing photosensitiveelements of the same construction and composition. The term inductionperiod as used herein is understood to pertain to that period of timefrom the contacting of the processing liquid with the exposedphotosensitive element to the start of development of silver halide. Inother words, the cesium hydroxide-containing processing compositions ofthis invention act as more efiicient initiators of development thanprior art alkaline materials.

In comparing a dye developer transfer color image formed by processingwith the novel cesium hydroxidecontaining processing composition of thisinvention with an image formed by another alkaline processingcomposition, a significant increase in the transfer rates of the dyes isnoted. This is particularly true of the anthraquinone dyes, particularlya cyan anthraquinone dye. For example, three-color negatives wereprocessed with equimolar aqueous solutions of sodium hydroxide andcesium hydroxide, each with a thickener added. After a 3 minuteimbibition with the sodium hydroxide solution, integral densities of0.33, 1.01, and 1.37 for cyan, magenta and yellow, respectively, wereobserved, while a negative processed for the same period of time withthe cesium hydroxide solution showed integral densities of 1.13, 1.46and 1.38 for cyan, magenta and yellow, respectively. A monochromecontaining a magenta anthraquinone dye developer showed approximately a10% increase in transfer density when processed with a cesium hydroxideprocessing composition.

From the foregoing,it can be seen that photographic processingcompositions employing cesium hydroxide are of particular interest whereit is desired to hasten the diffusion of a dye component of a negativethat is located most distant from an image-receiving element superposedon said negative. Dyes locatedin such a position must travel thegreatest distance during processing to reach the image-receiving layer,and therefore are often one of the major factors in determining thetotal necessary processing time. Cesium hydroxide speeds the diffusionof such a dye and particularly an arthraquinone dye.

The resultant increase in efficiency of dye transfer also permits theconstruction of photosensitive elements using less dye than would berequired if the processing were to be carried out with, e.g., a sodiumhydroxide processing composition. By this, it is meant that a moreefiicient use is made of the initial dye content, with a higherproportion being transferred to give the same transfer density. Anappropriate adjustment must be made in the ratio of thedyes in thenegative to provide for the differing degrees of increasein diffusionrates of the various dyes.

It has now been found that use of a cesium hydroxidecontainingprocessing solution makes more practical the use of thinner layers ofprocessing compositions than has been heretofore practical with priorart sodium hydroxide processing compositions. In the past, when anextremely.

has been found desirableto utilize a processing composition comprising,both cesium hydroxide and another 211- kaline material, e.g., sodiumhydroxide. By the use of cesium hydroxide as an additive to otheralkaline materials, in photographic processing compositions, it ispossible to achieve a significant degree, of the above-mentionedadvantages provided by cesium hydroxide processing compositions and atthe same time minimize the cost by also using sodium hydroxide. In suchmixtures, ratios of 0.252% cesium hydroxide and 4.5-7% sodium hydroxidehave been found particularly useful. The liquid processing compositionwithin the scope of this invention may also contain, as well as cesiumhydroxide alone or cesium hydroxide and sodium hydroxide, a dyedeveloper and, in some instances, it may contain an additional silverhalide developing agent. If the liquid processing composition is to beapplied to the emulsion by being spread thereon, preferably in arelativelythin, uniform layer, it may also include aviscosity-increasing compound constituting film-forming material of thetype which, when spread over a water-absorbent base, will form arelatively firm and relatively stable film. A preferredfilm-forming-material is a high molecular Weight polymer such as apolymeric, water-soluble ether inert to an alkali solution, as, forexample, a hydroxyethyl cellulose or sodium carboxymethyl cellulose.Other filmforming materials'or thickening agents whose ability; toincrease viscosity is substantially unaffected when left in solution fora long period of time may also be used.

The liquid processing composition may also contain antifoggants, e.g.,befizotriazole, and quaternary ammonium compounds, e.g.,N-phenethyl-u-picoliniu-m bromide, N-benzyl-a-picoliniumbromide, asdisclosed in the copending application of Milton Greenand Howard G.Rogers, Serial No. 50,851, filed August 22, 1960 (now U.S. Patent No.3,173,786, issued March 16, 1965).

The novel, processing compositions of this invention were tested indiffusion transfer processes on multilayer photosensitive elementsprepared in a manner similar to that disclosed in the above-mentionedUS.Patent No. 2,983,606 and in the copending application of EdwinH. Landand Howard G. Rogers, Serial No. 565,135, filed February 13, 1956, andimage-receiving elements comprising polyvinyl alcohol andpoly-4-vinylpyridine, such as those disclosed and claimed in thecopending application of Howard C. Haas, Serial No. 50,848, filed August22, 1960, now U.S. Patent No. 3,148,061, issued Sept. 8, 1964. Ingeneral, the photosensitive elements comprised a support carrying ared-sensitive silver halide emulsion stratum, a green-sensitive'silverhalide emulsion stratum and a blue-sensitive silverhalide emulsionstratum; said emulsions having dispersed in separate gelatin layersbehind them, respectively, a cyan dye developer, a magenta dye developerand a yellow dye developer, each pair of emulsion and dye developer.

layers being separated by an interlayer. The particular dye developersemployed inthe photosensitive elements were 1)1,4-bis-[a-methyl-fl-(2',5'-dihydroxyphenyl) ethylamino]-anthraquinone(a cyan dye developer), (2) 2 [p (2',5' dihydroxyphenethyl) phenylazo]4-isopropoxy-l-naphthol (a magenta dye developer), and (3)1-phenyl-3-N-n-hexyl-carbamyl 4 [p (hydroquinonyL ethyl)-phenylazo1-5-pyrazolone (a yellow dye developer).

In conducting the tests, areas of photosensitive elements were exposedto blue and green light only, red and blue light only, and red and greenlight only. The photosensitive elements were then imbibed for 3 minutesin superposed relationship with the aforementioned image-receivingelement, using the novel processing compositions of this invention. Theintegral cyan, magenta and yellow densities were then measured in thevarious areas of the image-receiving sheet.

The following aqueous processing compositions were used to process theabove-described photosensitive elements.

COMPOSITION NO. 1

Percent Cesium hydroxide 22.5 Hydroxyethyl cellulose 4.5

COMPOSITION NO. 2

Cesium hydroxide 18.8 Hydroxyethyl cellulose 4.5

COMPOSITION NO. 3

Cesium hydroxide 17.5 Hydroxyethyl cellulose 4.5

COMPOSITION NO. 4

Cesium hydroxide 22.5

Hydroxyethyl cellulose 4.5 N-phenethyl-a-picolinium bromide 2.0

COMPOSITION NO. 5

Cesium hydroxide 22.5 Hydroxyethyl cellulose 4.5 Benzotriazole 2.0

COMPOSITION NO. 6

Cesium hydroxide 22.5

Hydroxyethyl cellulose 4.5 N-phenethyl-a-picolinium bromide 2.0Benzotriazole 2.0

The above-described photosensitive elements were also processed with thefollowing sodium hydroxide processing compositions for purposes ofcomparison.

COMPOSITION NO. 7

The density measurements of photosensitive elements and image-receivingelements processed by the above processing compositions are set forthbelow in tabular form.

Integral Densities of the Dye Cyan Magenta Yellow Cesium HydroxideProcessing Oompositions:

NoIfi Sodium Hydroxide Processing Compositions:

As stated above, it has also been found desirable to utilize aqueousprocessing compositions comprising both cesium hydroxide and anotheralkaline material, e.g., sodium hydroxide. The processing compositionset forth below illustrates this embodiment of the invention.

COMPOSITION NO. 14

Sodium hydroxide Cesium hydroxide Hydroxyethyl cellulose BenzotriazoleN-benzyl-a-picolinium bromide As previously noted, use of cesiumhydroxide-containing processing compositions results in reducedimbibition times and permits the use of thinner layers of the processingcomposition. These advantages are illustrated by the experimentsdescribed below using the above composition 14 and the followingcomposition 15:

COMPOSITION NO. 15

Gm. Sodium hydroxide 5.17 Hydroxyethyl cellulose 4.5 Benzotriazole 2.3N-benZyl-a-picolinium bromide 2.3 Sodium thiosulfate 1.15

In conducting the tests, areas of photosensitive elements were exposedto (1) blue and green light only, (2) red and blue light only, (3) redand green light only, (4) totally exposed, and (5) no exposure. Onephotosensitive element was processed with the cesium hydroxidecontaining composition No. 14 at a gap of 0.0032 in., for 1 /2 minutes.The second photosensitive element was processed with the sodiumhydroxide processing composition No. 15 at a gap of 0.0036 in., for 2minutes. The integral densities in the various areas of the twoimage-receiving sheets, appearing in tabular form below, were measuredby reflectance using red, green and blue filters.

Transfer densities COMPOSITION NO. 14 (1.5 MIN. IMBIBITION) Exposure RedGreen Blue Filter Filter Filter Blue and Green 1. 46 0.52 0.43 Red andBlue 0. l2 0. 71 0. 51 Red and Green 0. 08 0. 22 1. 12 Total Exposure 0.08 0. 14 0. 17 No Exposure 1. 79 2. 04 2. 21

Use of a sodium hydroxide processing composition containing 0.5%, byweight, cesium hydroxide gave a increase in transfer image density whenused to process a monochrome negative containing 1,4-diamiuo-2-[(2',5-dihydroxy) hydrocinnamido amoxy anthraquinone, as compared withthe magenta transfer density obtained in the use of substantially thesame processing composition except that cesium hydroxide was notpresent.

In many transfer processes employing dye developers, it is desirable toeffect development in the presence of a substantially colorless,auxiliary or accelerating silver halide developing agent, such asphenyl-hydroquinone, toluhydroquinone,4,4-dimethyl-l-phenyl-3-pyrazolidone, 4-methylphenyl-hydroquinone, etc.This auxiliary developing agent may be present initially in theprocessing solution, or it may be contained in one or more layers of thenegative, e.g., in an interlayer and/ or in an overcoat on the negative.

The novel processing compositions have also been found useful inprocessing photosensitive elements with the image-receiving elements setforth in the copending application of Edwin H. Land, Serial No. 234,864,filed November 1, 1962, wherein the image-receiving element contains alayer of polymeric acid. The above-mentioned ability to shorten theinduction time, increase the rate of diffusion of the dyes and increasethe density of the dyes is also noted on the aforementionedimage-receiving elements containing a layer of polymeric acid betweenthe image-receiving layer and the support.

The .novel processing composition of this invention may also be used inconventional development processes, black and white as well as color.

It will be understood that cesium hydroxide also may be formed, in situ,as by adding an appropriate cesium salt, e.g., cesium nitrate, to asolution containing, e.g., sodium hydroxide.

Since certain changes may be made in the above prodnet and processWithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description shall beinterrupted as illustrative and not in a limiting sense...

What is claimed is:

1. A photographic developing composition comprising an aqueous solutionof cesium hydroxide and a quaternary ammonium compound.

2. A product as defined in claim 1 wherein said cesium hydroxidecomprises from about 0.1 to 25% by weight of the solution, and saidsolution contains a silver halide developing agent.

3. A product as defined in claim 1 wherein said developing compositioncontains a thickening agent.

4. A product as defined in claim 1 wherein said developing compositioncontains an antifoggant.

5. A process of forming a photographic image in color, comprisingdeveloping an exposed silver halide emulsion in the presence of anaqueous alkaline solution comprising cesium hydroxide and at least onedye developer to thereby provide an imagewise distribution of unoxidizeddye developer, and transferring at least a part of said imagewisedistribution of unoxidized dye developerato an image-receiving layer insuperposed relationship with said silver halide emulsion to impart a dyeimageto said imagereceiving layer.

6. A process as defined in claim 5 wherein said cesium hydroxidecomprises from about 0.1 to 25% by weight of the aqueous alkalinesolution.

7. The process as defined in claim 5 wherein said dye developer isdisposed, prior to exposure, in the photosensitive element comprisingsaid exposed silver halide emulsion, and the solution containing saiddye developer is formed by permeating said photosensitive element withsaid aqueous alkaline solution.

8. The process as defined in claim 5 wherein said aqueous alkalinesolution is introduced by being spread in a substantially uniform layer,as said photosensitive element and image-receiving layer are broughtinto superposed relationship.

9. The process as defined in claim 5 wherein said aqueous alkalinesolution contains a thickener for increasing viscosity and facilitatingthe spreading thereof between said photosensitive element and saidimage-receiving layer.

10. The process as defined in claim 5 wherein said dye developer is ananthraquinone dye developer, whereby the transfer of said anthraquinonedye developer is substantially greater as a result of processing withcesium hydroxide. solution. 7

11. The process as defined in claim 10 wherein said dye developer is1,4-bis-[rx-methyl-[i-(2',5'-dihydroxyphenyl -ethylamino]-anthraquinone.

12. The process as defined in claim 5 wherein said photosensitiveelement contains a cyan,a magenta and a yellow dye developer.

13. A process of developing an exposed silver halide emulsion whichcomprises treating said emulsion with an aqueous alkaline solutioncomprising cesium hydroxide and at least one dye developer.

14. A process as defined in claim 13 wherein said dye developer is ananthraquinone dye developer.

15. A process as defined in claim 14 wherein said anthraquinone dyedeveloper is 1,4-bis-[a-methyl-B-(2',5'- dihydroxyphenyl) -ethylamino]-anthraquinone.

16. A process as defined in claim 13 wherein said solution containsabout 0.1 to 25% cesium hydroxide, by weight.

17. A photographic product for use in a diffusion transfor processcomprising a photosensitive element, including a silver halide emulsion,having at least one dye developer in a layer of said photosensitiveelement, each said dye developer being adapted to form an imagewisedistribution of mobile dye developer as a function of development of thesilver halide emulsion, an imagereceiving element, and a rupturablecontainer holding an aqueous alkaline processing solution, said aqueousalkaline processing solution including cesium hydroxide, said elementsbeing capable of being superposed, and said container being associatedwith said elements in such a manner that the container, upon beingruptured, is capable of releasing said processing solution between saidsuperposed elements to permeate said superposed elements, saidimage-receiving element comprising a support bearing a dyeableimage-receiving stratum.

18. A product as defined in claim 17 wherein said photosensitive elementcontains a cyan, a magenta and a yellow dye developer.

19. A product as defined in claim 17 wherein said aqueous alkalinesolution contains a thickening agent.

20. A product as defined in claim 17 wherein said cesium hydroxidecomprises about 0.1 to 25% by weight of the aqueous alkaline solution.

21. A product as defined in claim 17 wherein said dye develowr is1,4-bis-[u-methyl-fi-(2',5'-dihydroxyphenyl)- ethylamino] -anthraquinone.

22. A product as defined in claim 18 wherein said dye developers are1,4-bis-[u-methyl B (2,5' dihydroxyphenyl) ethylamino] anthraquinone,2-[p-(2',5'-dihydroxyphenethyl)-5-phenylazo]-4-propoxy-1-naphthol and 101-pheny1-3-N-n-hexyl-carbamyl 4 [P-(hydroquinonylethyl) -phenylazo]-5-pyrazolone.

23. A photographic developing composition as defined in claim 1 whereinsaid solution also contains sodium hydroxide.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

J. T. BROWN, Assistant Examiner.

5. A PROCESS OF FORMING A PHOTOGRAPHIC IMAGE IN COLOR, COMPRISINGDEVELOPING AN EXPOSED SILVER HALIDE EMULSION IN THE PRESENCE OF ANAQUEOUS ALKALINE SOLUTION COMPRISING CESIUM HYDROXIDE AND AT LEAST ONEDYE DEVELOPER TO THEREBY PROVIDE AN IMAGEWISE DISTRIBUTION OF UNOXIDIZEDDYE DEVELOPER, AND TRANSFERRING AT LEAST A PART OF SAID IMAGEWISEDISTRIBUTION OF UNOXIDIZED DYE DEVELOPER TO AN IMAGE-RECEIVING EMULSIONTO IMPART A DYE IMAGE TO SAID IMAGESILVER HALIDE EMULSION TO IMPART ADYE IMAGE TO SAID IMAGERECEIVING LAYER.